Kurt J. Lesker 979 Series, Operation And Maintenance Manual

Page: 51 / 54

Series 979 ATV Transducer 51
R+
Δ
R
R+
Δ
R
R-
Δ
R
R-
Δ
R
V
b
V
out
N
Silicon
SiO
2
Depletion region
Implanted
resistors
Diaphragm
R2
R4
R1 R3
MicroPirani Sensor
The MicroPirani sensor functions the same as a traditional Pirani sensor, but
instead of a heated wire, a thin film Nickel resistive element is deposited onto
a silicon substrate. This heated filament is maintained at a constant
temperature above the ambient temperature of the substrate. A solid-state
MicroPirani sensor has several advantages over a wire based Pirani sensor.
The operational parameters are controlled and optimized to decrease the end
loss and radiation errors, the integrated temperature sensors improve the
temperature compensation performance, and the small geometry decreases
the thermal lag time, ensuring faster response time. These improvements
allow the MicroPirani sensor to operate down to 10
-5
Torr, two decades lower
than traditional Pirani sensors. The smaller distance between the heated
filament and the cold substrate increases the pressure measurement range in
the higher-pressure regions.